The additional diagnostic value of a single-session combined scintigraphic and ultrasonographic examination in patients with thyroid and parathyroid diseases.
OBJECTIVE
The aim of this study was to investigate the diagnostic efficacy and the clinical impact of scintigraphy combined with ultrasonography (USG) in the management of thyroid and parathyroid disorders in a large series of patients.


METHODS
A total of 387 consecutive patients referred to the Nuclear Medicine Department of Hacettepe University in the period from January to September 2007 for investigating a thyroid (N. 339 patients: 232 females and 107 males, mean age+/-SD=48.9+/-13.6 years) or a parathyroid disease (N. 48 patients: 34 females and 14 males, mean age+/-SD=47.4+/-9.6 years) were prospectively evaluated, systematically performing both scintigraphy and USG in a single-day session. All the examinations were independently reviewed by two nuclear medicine physicians; in cases of discrepancy (3%) a final diagnosis was reached by consensus. For thyroid pathologies, USG results were considered to provide additional diagnostic information over scintigraphy: 1) if more nodules were identified; 2) if an irregular hyperactive area at scintigraphy suspicious for the presence of a nodule was clearly characterized at USG; 3) if a nodule missed at scintigraphy because of small size (<1 cm) was well depicted at USG, thus allowing an USG-guided fine needle aspiration cytology (FNAC) to reach a final diagnosis. For parathyroid pathologies, USG was considered to provide additional diagnostic information over scintigraphy if a low intensity radiotracer retention from the parathyroid suspected of being a parathyroid enlargement was clearly depicted at USG. In thyroid diseases, scintigraphy was considered to provide additional diagnostic information over USG, if the functional status of a diffuse or uni- or multi-nodular goiter were clearly defined at scintigraphy. In parathyroid diseases, scintigraphy was considered to provide additional diagnostic information over USG, if the differential diagnosis between a lymph node or a muscle or a vessel depicted at USG was clearly defined as a parathyroid enlargement at scintigraphy. Lastly, the clinical impact of the single-day combined scintigraphic/USG protocol was evaluated.


RESULTS
USG. In the thyroid diseases group, USG was particularly useful: 1) to detect additional nodules in glands with suppressed thyroid tissue; 2) to disclose small thyroid nodules (<1 cm) in which it was possible to perform a USG-FNAC. In the parathyroid diseases group, USG was particularly useful for the detection of parathyroid enlargements not visualized at scintigraphy because characterized by a rapid wash-out of the radiotracer and thus by a low radioactivity intensity in the delayed scintigraphic images. Scintigraphy. In the thyroid diseases group, scintigraphy was particularly useful: 1) to diagnose a diffuse hyperfunctioning thyroid gland, and to differentiate in multinodular goiters the hyper- from the hypo-functioning nodules. In the hyperparathyroid diseases group, scintigraphy was particular useful in making a differential diagnosis between a true parathyroid enlargement vs. a lymph node or a muscle or a vessel as depicted at USG, and in cases with deeply or ectopically-positioned parathyroid glands. Combined imaging approach. Combined interpretation provided additional benefit in 225 of 339 patients (64.4%). Overall, using the combined scintigraphic/USG single-day protocol, in the thyroid diseases group the therapeutic strategy (drug therapy vs radioiodine therapy vs surgery) was changed in 176/225 patients (78.2%, P<0.001 by chi(2) of Pearson), and in the parathyroid disease group the therapeutic strategy (medical therapy vs surgery) was changed in 18/48 patients (37.5%, P<0.01 by chi2 test of Pearson).


CONCLUSIONS
In agreement with some previous published experiences, the combined single-day scintigraphic/USG protocol systematically adopted in a large series of consecutive patients with thyroid and parathyroid diseases, enrolled in a limited period of time, proved to significantly increase the global diagnostic accuracy and to change the therapeutic strategy in more than two third of patients with a thyroid disease and in more than one third of patients with a parathyroid disease.
Gedik
G K
GK
Department of Nuclear Medicine, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
Bozkurt
F M
FM
Ugur
O
O
Grassetto
G
G
Rubello
D
D
D000328:Adult; D044963:Biopsy, Fine-Needle; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010279:Parathyroid Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000628:therapy; D010280:Parathyroid Glands / Q000000981:diagnostic imaging*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D013670:Sodium Pertechnetate Tc 99m; D017256:Technetium Tc 99m Sestamibi; D013959:Thyroid Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000628:therapy; D013961:Thyroid Gland / Q000000981:diagnostic imaging*; D015899:Tomography, Emission-Computed, Single-Photon; D014463:Ultrasonography
D019275:Radiopharmaceuticals; D017256:Technetium Tc 99m Sestamibi; D013670:Sodium Pertechnetate Tc 99m